The present invention is related to fluid pressure brake apparatus for a railway vehicle and more particularly to fluid pressure brake apparatus embodying means for automatically adjusting the degree of brake application in accordance with varying load conditions of a railway freight vehicle.
Typically, load adjusted fluid pressure brake control apparatus for railway vehicles operating in freight service employs empty/load type brake control, which is a two-step control wherein normal brake pressures are realized under load conditions and a modulated brake pressure is realized under empty conditions of vehicle loading. In modulating brake pressures under empty conditions, the occasion of slid flat wheels, as well as rough train action due to differently loaded cars or groups of cars is eliminated.
Because of the various load conditions of the freight cars comprising a train, however, empty/load type brake control is not completely satisfactory, since cars having a partial load may be underbraked or overbraked depending upon the preselected changeover point between the empty/load setting. This situation is even more critical with the modern lightweight cars, which have a wider range between their gross and tare weights.